In the environmentally sound processing e.g. of recyclable material mixtures, container waste, and components similar to household waste, the problem arises of separating specific categories of recyclables materials as completely as possible. Both the sieving technique and the air separation technique are limited. Since organic, highly adhesive components or fine dust components also often occur in the aforementioned recyclables, separation by air or sieves involves corresponding disadvantages.
In individual cases it is unavoidable that vastly different collected material, e.g. liftings, are to be sorted into easily reclaimable organic components and heavy fractions intended for recyclables or dumps.
In recent times, repeated efforts have been made for a recycling which is as complete as possible, at least with glass receptacles, cans, aluminum cans, plastic bottles, etc. The newly developing flow of material must be separated in an efficient manner, so that the individual base materials such as glass and aluminum can be returned to other respective processing centers at a minimum of expense. In the case of glass, it is required that there be as little glass breakage as possible. This rules out an excessively large massing. The consequence of this would be many small plants, if possible in the vicinity of the consumers.
The current practice is sorting into different categories of material by hand. A typical characteristic of all highly industrialized societies is the high cost for all manual labor. The required high expenditure on manual labor often stands in the way of the complete success of a genuine recycling.
A solution is known in U.S. Pat. No. 4,760,925 in which the mixture is separated into a heavy fraction and a light fraction by means of a brush shaft following a pre-separation by means of a slope conveyor belt. In this patent, heavy parts fall down directly without being influenced by the brush movement. Tests conducted by the present Applicant showed only an insufficient or fluctuating separation quality when the product was conveyed, as it were, frontally to the sorting drum, and the heavy fraction is sorted out opposite the movement direction of the sorting drum and the lighter fraction is lifted over around the drum radius and thrown to the other side of the drum.